Crown Macro-Tech 602, Macro-Tech 1202 User manual

Models:
Macro-Tech® 602, 1202 & 2402
Some models may be exported under the name Amcron .
®
127240-2
07/00
© 2000 by Crown International, Inc., P.O. Box 1000, Elkhart, IN 46515-1000 U.S.A.
Telephone: [phone]. Fax: [phone]. Macro-Tech®amplifiers are produced by
the Professional Audio Unit of Crown International, Inc. Trademark Notice: PIP
™
, PIP2
™
,
SmartAmp
™and
Grounded Bridge
™are trademarks and
Amcron
®,
Crown
®,
Macro-
Tech
®,
IOC
®,
ODEP
®, and
IQ System
®are registered trademarks of Crown International,
Inc. Other trademarks are the property of their respective owners.

WORLDWIDE
SUMMARY OF WARRANTY
The Cro n Audio Division of Cro n International, Inc., 1718 West
Misha aka Road, Elkhart, Indiana 46517-4095 U.S.A. arrants to you, the
ORIGINAL PURCHASER and ANY SUBSEQUENT OWNER of each
NEW Cro n1 product, for a period of three (3) years from the date of
purchase by the original purchaser (the “ arranty period”) that the ne
Cro n product is free of defects in materials and orkmanship, and e
further arrant the ne Cro n product regardless of the reason for failure,
except as excluded in this Cro n Warranty.
1
Note: If your unit bears the name “Amcron,” please substitute it for the
name “Cro n” in this arranty.
IT MS XCLUD D FROM THIS CROWN WARRANTY
This Cro n Warranty is in effect only for failure of a ne Cro n product
hich occurred ithin the Warranty Period. It does not cover any product
hich has been damaged because of any intentional misuse, accident,
negligence, or loss hich is covered under any of your insurance contracts.
This Cro n Warranty also does not extend to the ne Cro n product if the
serial number has been defaced, altered, or removed.
WHAT TH WARRANTOR WILL DO
We ill remedy any defect, regardless of the reason for failure (except as
excluded), by repair, replacement, or refund. We may not elect refund
unless you agree, or unless e are unable to provide replacement, and
repair is not practical or cannot be timely made. If a refund is elected, then
you must make the defective or malfunctioning product available to us free
and clear of all liens or other encumbrances. The refund ill be equal to the
actual purchase price, not including interest, insurance, closing costs, and
other finance charges less a reasonable depreciation on the product from
the date of original purchase. Warranty ork can only be performed at our
authorized service centers. We ill remedy the defect and ship the product
from the service center ithin a reasonable time after receipt of the
defective product at our authorized service center.
HOW TO OBTAIN WARRANTY S RVIC
You must notify us of your need for arranty service not later than ninety
(90) days after expiration of the arranty period. All components must be
shipped in a factory pack. Corrective action ill be taken ithin a
reasonable time of the date of receipt of the defective product by our
authorized service center. If the repairs made by our authorized service
center are not satisfactory, notify our authorized service center
immediately.
DISCLAIM R OF CONS QU NTIAL AND INCID NTAL DAMAG S
YOU ARE NOT ENTITLED TO RECOVER FROM US ANY INCIDENTAL
DAMAGES RESULTING FROM ANY DEFECT IN THE NEW CROWN
PRODUCT. THIS INCLUDES ANY DAMAGE TO ANOTHER PRODUCT
OR PRODUCTS RESULTING FROM SUCH A DEFECT.
WARRANTY ALT RATIONS
No person has the authority to enlarge, amend, or modify this Cro n
Warranty. This Cro n Warranty is not extended by the length of time hich
you are deprived of the use of the ne Cro n product. Repairs and
replacement parts provided under the terms of this Cro n Warranty shall
carry only the unexpired portion of this Cro n Warranty.
D SIGN CHANG S
We reserve the right to change the design of any product from time to time
ithout notice and ith no obligation to make corresponding changes in
products previously manufactured.
L GAL R M DI S OF PURCHAS R
No action to enforce this Cro n Warranty shall be commenced later than
ninety (90) days after expiration of the arranty period.
THIS STAT M NT OF WARRANTY SUP RS D S ANY OTH RS
CONTAIN D IN THIS MANUAL FOR CROWN PRODUCTS.
9/90
NORTH AMERICA
SUMMARY OF WARRANTY
The Cro n Audio Division of Cro n International, Inc., 1718 West Misha aka
Road, Elkhart, Indiana 46517-4095 U.S.A. arrants to you, the ORIGINAL
PURCHASER and ANY SUBSEQUENT OWNER of each NEW Cro n product,
for a period of three (3) years from the date of purchase by the original purchaser
(the “ arranty period”) that the ne Cro n product is free of defects in materials
and orkmanship. We further arrant the ne Cro n product regardless of the
reason for failure, except as excluded in this Warranty.
IT MS XCLUD D FROM THIS CROWN WARRANTY
This Cro n Warranty is in effect only for failure of a ne Cro n product hich
occurred ithin the Warranty Period. It does not cover any product hich has
been damaged because of any intentional misuse, accident, negligence, or loss
hich is covered under any of your insurance contracts. This Cro n Warranty
also does not extend to the ne Cro n product if the serial number has been
defaced, altered, or removed.
WHAT TH WARRANTOR WILL DO
We ill remedy any defect, regardless of the reason for failure (except as
excluded), by repair, replacement, or refund. We may not elect refund unless you
agree, or unless e are unable to provide replacement, and repair is not practical
or cannot be timely made. If a refund is elected, then you must make the defective
or malfunctioning product available to us free and clear of all liens or other
encumbrances. The refund ill be equal to the actual purchase price, not
including interest, insurance, closing costs, and other finance charges less a
reasonable depreciation on the product from the date of original purchase.
Warranty ork can only be performed at our authorized service centers or at the
factory. We ill remedy the defect and ship the product from the service center
or our factory ithin a reasonable time after receipt of the defective product at our
authorized service center or our factory. All expenses in remedying the defect,
including surface shipping costs in the United States, ill be borne by us. (You
must bear the expense of shipping the product bet een any foreign country and
the port of entry in the United States and all taxes, duties, and other customs fees
for such foreign shipments.)
HOW TO OBTAIN WARRANTY S RVIC
You must notify us of your need for arranty service not later than ninety (90)
days after expiration of the arranty period. All components must be shipped in
a factory pack, hich, if needed, may be obtained from us free of charge.
Corrective action ill be taken ithin a reasonable time of the date of receipt of
the defective product by us or our authorized service center. If the repairs made
by us or our authorized service center are not satisfactory, notify us or our
authorized service center immediately.
DISCLAIM R OF CONS QU NTIAL AND INCID NTAL DAMAG S
YOU ARE NOT ENTITLED TO RECOVER FROM US ANY INCIDENTAL
DAMAGES RESULTING FROM ANY DEFECT IN THE NEW CROWN
PRODUCT. THIS INCLUDES ANY DAMAGE TO ANOTHER PRODUCT OR
PRODUCTS RESULTING FROM SUCH A DEFECT. SOM STAT S DO
NOT ALLOW TH XCLUSION OR LIMITATIONS OF INCID NTAL OR
CONS QU NTIAL DAMAG S, SO TH ABOV LIMITATION OR
XCLUSION MAY NOT APPLY TO YOU.
WARRANTY ALT RATIONS
No person has the authority to enlarge, amend, or modify this Cro n Warranty.
This Cro n Warranty is not extended by the length of time hich you are
deprived of the use of the ne Cro n product. Repairs and replacement parts
provided under the terms of this Cro n Warranty shall carry only the unexpired
portion of this Cro n Warranty.
D SIGN CHANG S
We reserve the right to change the design of any product from time to time ithout
notice and ith no obligation to make corresponding changes in products
previously manufactured.
L GAL R M DI S OF PURCHAS R
THIS CROWN WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, YOU
MAY ALSO HAVE OTHER RIGHTS WHICH VARY FROM STATE TO STATE.
No action to enforce this Cro n Warranty shall be commenced later than ninety
(90) days after expiration of the arranty period.
THIS STAT M NT OF WARRANTY SUP RS D S ANY OTH RS
CONTAIN D IN THIS MANUAL FOR CROWN PRODUCTS.
9/90
Telephone: [phone]. Facsimile: 219-294-8301
Telephone: [phone]. Facsimile: 219-294-8301
THREE YEAR
FULL WARRANTY
YEAR
3
YEAR
3

The information furnished in this manual does not include all of the details of design, production, or variations of the
equipment. Nor does it cover every possible situation which may arise during installation, operation or mainte-
nance. If your unit bears the name “Amcron,”please substitute it for the name “Crown”in this manual. If you need
special assistance beyond the scope of this manual, please contact our Technical Support Group.
Crown Audio Technical Support Group
Plant 2 SW, 1718 W. Misha aka Rd., Elkhart, Indiana 46517 U.S.A.
Phone: [phone] (North America, Puerto Rico and Virgin Islands) or 219-294-8200
Fax: [phone] Fax Back (North America only): 800-294-4094 or 219-293-9200
Fax Back (International): 219-294-8100 Internet: http:// .cro naudio.com
IMPORTANT
TH MACRO-T CH 2402 R QUIR S CLASS 1
OUTPUT WIRING. TH MACRO-T CH 602 &
1202 R QUIR CLASS 2 OUTPUT WIRING.
Printed on
recycled paper.
The lightning bolt
triangle is used to
alert the user to the
risk of electric shock.
The exclamation point
triangle is used to alert the
user to important operating
or maintenance instructions.
WARNING
TO R DUC TH RISK OF L CTRIC
SHOCK, DO NOT XPOS THIS
QUIPM NT TO RAIN OR MOISTUR !
Magnetic Field
CAUTION! Do not locate sensitive high-gain
equipment such as preamplifiers or tape decks
directly above or below the unit. Because this
amplifier has a high power density, it has a strong
magnetic field which can induce hum into unshielded
devices that are located nearby. The field is stron-
gest just above and below the unit.
If an equipment rack is used, we recommend locat-
ing the amplifier(s) in the bottom of the rack and the
preamplifier or other sensitive equipment at the top.
C A U T I O N
RISK OF L CTRIC SHOCK
DO NOT OP N
TO PR V NT L CTRIC SHOCK DO
NOT R MOV TOP OR BOTTOM
COV RS. NO US R S RVIC ABL
PARTS INSID . R F R S RVICING TO
QUALIFI D S RVIC P RSONN L.
DISCONN CT POW R CORD B -
FOR R MOVING R AR INPUT
MODUL TO ACC SS GAIN SWITCH.
A V I S
RISQU D CHOC ÉL CTRIQU
N’OUVR Z PAS
À PRÉV NIR L CHOC ÉL CTRIQU
N’ NL V Z PAS L S COUV RCL S. IL
N’Y A PAS D S PARTI S
S RVIC ABL À L’INTÉRI UR. TOUS
R PARATIONS DOIT TR FAIR PAR
P RSONN L QUALIFIÉ S ULM NT.
DÉBRANCH R LA BORN AVANT
D’OUVRIR LA MODUL N ARRIÈR .

Macro-Tech
®
602/1202/2402 Po er Amplifiers
Page 4
Reference Manual
Important Safety Instructions
1) Read these instructions.
2) Keep these instructions.
3) Heed all warnings.
4) Follow all instructions.
5) Do not use this apparatus near water.
6) Clean only with a dry cloth.
7) Do not block any ventilation openings. Install in accordance
with the manufacturer’s instructions.
8) Do not install near any heat sources such as radiators, heat
registers, stoves, or other apparatus that produce heat.
9) Do not defeat the safety purpose of the polarized or grounding-
type plug. A polarized plug has two blades with one wider than
the other. A grounding-type plug has two blades and a third
grounding prong. The wide blade or the third prong is pro-
vided for your safety. If the provided plug does not fit into your
outlet, consult an electrician for replacement of the obsolete
outlet.
10) Protect the power cord from being walked on or pinched, par-
ticularly at plugs, convenience receptacles, and the point
where they exit from the apparatus.
11) Only use attachments/accessories specified by the manufac-
turer.
12) Use only with a cart, stand, bracket, or table specified by the
manufacturer, or sold with the apparatus. When a cart is used,
use caution when moving the cart/apparatus combination to
avoid injury from tip-over.
13) Unplug this apparatus during lightning storms or when unused
for long periods of time.
14) Refer all servicing to qualified service personnel. Servicing is
required when the apparatus has been damaged in any way,
such as power-supply cord or plug is damaged, liquid has
been spilled or objects have fallen into the apparatus, the ap-
paratus has been exposed to rain or moisture, does not oper-
ate normally, or has been dropped.
15) To reduce the risk of fire or electric shock, do not expose this
apparatus to rain or moisture.

Macro-Tech
®
602/1202/2402 Po er Amplifiers
Page 5
Reference Manual
CONTENTS
1 Welcome ............................................................................ 7
1.1 Unpacking ................................................................... 7
1.2 Features ....................................................................... 7
2 Controls, Indicators & Connectors ................................... 9
3 Installation ....................................................................... 11
3.1 Mounting ................................................................... 11
3.2 Cooling ...................................................................... 11
3.3 Wiring ........................................................................ 12
3.3.1 Stereo (Two-Channel) Operation ...................... 12
3.3.2 Bridge-Mono Operation ................................... 13
3.3.3 Parallel-Mono Operation .................................. 14
3.3.4 Input Connection ............................................. 15
3.3.5 Output Connection .......................................... 17
3.3.6 Additional Load Protection ............................... 19
3.4 AC Power Requirements ............................................ 19
4 Operation ......................................................................... 20
4.1 Precautions ................................................................ 20
4.2 Indicators................................................................... 20
4.3 Protection Systems .................................................... 22
4.3.1 ODEP .............................................................. 22
4.3.2 Standby Mode ................................................. 22
4.3.3 Transformer Thermal Protection ....................... 22
4.3.4 Fuses and Circuit Breakers .............................. 23
4.4 Controls ..................................................................... 23
4.5 Filter Cleaning ............................................................ 24
5 Technical Information...................................................... 25
5.1 Overview ................................................................... 25
5.2 Circuit Theory ............................................................ 25
5.2.1 Stereo Operation ............................................. 25
5.2.2 Bridge-Mono Operation ................................... 27
5.2.3 Parallel-Mono Operation .................................. 27
6 Specifications .................................................................. 28
7 AC Power Draw & Thermal Dissipation ........................... 37
8 Accessories ..................................................................... 39
8.1 PIP and PIP2 Modules ................................................ 39
8.2 Cooling Fan Options .................................................. 41
8.3 Level Control Security Kit ........................................... 41
9 Service ............................................................................. 42
9.1 Worldwide Service ..................................................... 42
9.2 North American Service ............................................. 42
9.2.1 Service at a N. American Service Center ......... 42
9.2.2 Factory Service ............................................... 42

Macro-Tech
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Reference Manual
ILLUSTRATIONS
1.1 Macro-Tech Amplifier ................................................................ 7
2.1 Front Panel Controls & Indicators ............................................... 9
2.2 Rear Panel Controls & Connectors .......................................... 10
3.1 Mounting Dimensions .............................................................. 11
3.2 Top View of a Rack-Mounted Unit ............................................ 11
3.3 Proper Air Flow in a Rack Cabinet ........................................... 11
3.4 Stereo Wiring .......................................................................... 12
3.5 Bridge-Mono Wiring ................................................................ 13
3.6 Parallel-Mono Wiring ............................................................... 14
3.7 Unbalanced Input Wiring ......................................................... 15
3.8 Balanced Input Wiring ............................................................. 15
3.9 Balanced and Unbalanced Phone Plugs ................................. 15
3.10 Infrasonic Filter Capacitors ...................................................... 16
3.11 Unbalanced RFI Filters ............................................................ 16
3.12 Balanced RFI Filters ................................................................ 16
3.13 Wire Size Nomograph ............................................................. 17
3.14 Inductive Load (Transformer) Network ..................................... 18
3.15 Loudspeaker Fuse Nomograph ............................................... 19
4.1 Indicators ................................................................................ 20
4.2 Macro-Tech ODEP and Signal/IOC Indicator States ................. 21
4.3 Input Sensitivity and Ground Lift Switches ............................... 23
5.1 Circuit Block Diagram ............................................................. 26
6.1 Macro-Tech 602 Minimum Power Matrix .................................. 30
6.2 Macro-Tech 1202 Minimum Power Matrix ................................ 31
6.3 Macro-Tech 2402 Minimum Power Matrix ................................ 31
6.4 Macro-Tech 602 Maximum Power Matrix ................................. 32
6.5 Macro-Tech 1202 Maximum Power Matrix ............................... 33
6.6 Macro-Tech 2402 Maximum Power Matrix ............................... 33
6.7 Typical Frequency Response .................................................. 34
6.8 Typical Damping Factor .......................................................... 34
6.9 Typical Output Impedance ...................................................... 34
6.10 Typical Phase Response ......................................................... 35
6.11 Typical Crosstalk for the Macro-Tech 602 ................................. 35
6.12 Typical Crosstalk for the Macro-Tech 1202 ............................... 36
6.13 Typical Crosstalk for the Macro-Tech 2402 ............................... 36
7.1 Macro-Tech 602 Power Draw, Current Draw and
Thermal Dissipation at Various Duty Cycles ............................. 37
7.2 Macro-Tech 1202 Power Draw, Current Draw and
Thermal Dissipation at Various Duty Cycles ............................. 38
7.3 Macro-Tech 2402 Power Draw, Current Draw and
Thermal Dissipation at Various Duty Cycles ............................. 38
8.1 PIP2 Adapter Connection ........................................................ 39
8.2 Installing a PIP Module ............................................................ 39
8.3 Installing a PIP2 Module .......................................................... 39
8.4 Installing a Level Control Shaft Lock ........................................ 41

Macro-Tech
®
602/1202/2402 Po er Amplifiers
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Reference Manual
1 Welcome
Congratulations on your purchase of the renowned
Macro-Tech
®professional power amplifier. Macro-Tech
amplifiers are designed to provide enormous levels of
pure, undistorted power in a rugged low-profile pack-
age—making them the choice for pro sound reinforce-
ment. They utilize our patented ODEP
®protection
circuitry to keep the show going long after other ampli-
fiers have shut down. And with their PIP ™expandability,
Macro-Tech amplifiers can be easily customized with
one of our many optional input modules (see Section 8
for a list of available PIPs).
This manual will help you successfully install and use
your new amplifier. Please read all instructions, warn-
ings and cautions. Be sure to read Sections 3.3.2 and
3.3.3 if you plan to use one of the amplifier’s two mono
modes. Also for your protection, please send in your
warranty registration card today and save your bill of
sale because it is your official proof of purchase.
1.1 Unpacking
Please unpack and inspect your new amplifier for any
damage that may have occurred during transit. If dam-
age is found, notify the transportation company imme-
diately. Only you, the consignee, may initiate a claim for
shipping damage. Crown will be happy to cooperate
fully as needed. Save the shipping carton as evidence
of damage for the shipper’s inspection.
Even if the unit arrived in perfect condition, as most do,
save all packing materials so you will have them if you
ever need to transport the unit. N V R SHIP TH UNIT
WITHOUT TH FACTORY PACK.
1.2 Features
Macro-Tech amplifiers use cutting edge technology to
deliver the ultimate in power and value for their size,
weight and price. They offer numerous advantages over
conventional designs and provide benefits you can’t get
in amplifiers from any other manufacturer.
Here are some of their many features:
❏Crown’s Grounded Bridge ™design delivers large voltage
swings without using easily stressed output-transistor con-
figurations like conventional amplifiers. The results are
lower distortion and superior reliability.
❏Patented ODEP (Output Device Emulation Protection) cir-
cuitry compensates for overheating and overload to keep
the amplifier working when others would fail.
❏
IOC
®(Input/Output Comparator) circuitry immediately
alerts of any distortion exceeding 0.05%, providing dy-
namic
proof of distortion-free performance .
❏PIP (Programmable Input Processor) connector accepts
accessories that tailor the amplifier to suit specific appli-
cations.
❏nhanced
PIP2
™™
™™
™ (Programmable Input Processor)
connector accepts new accessory modules that further
tailor the amplifier to suit specific applications,
including wideband load current monitoring..
..
.
❏Two mono modes (Bridge-Mono and Parallel-Mono) for
driving a wide range of load impedances.
❏Very low harmonic and intermodulation distortion result in
the best
dynamic transfer function in the industry.
❏High damping factor provides superior control over low-
frequency drivers for a clean, accurate low end.
❏Full protection against shorted outputs, mismatched
loads, input/output DC, general overheating, high-fre-
quency overloads and internal faults.
❏Dedicated power supply transformers isolate channels in
Stereo mode for superb crosstalk characteristics and reli-
ability—each channel is virtually a separate amplifier.
❏Balanced inputs with internal three-position sensitivity
Fig. 1.1 Macro-Tech Amplifier

Macro-Tech
®
602/1202/2402 Po er Amplifiers
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Reference Manual
switch and adjustable front-panel level controls.
❏Versatile 5-way binding posts make it easy to connect
output wiring.
❏Full protection from shorted, open and mismatched
loads, general overheating. DC, high-frequency over-
loads, and full internal fault protection are provided by
our latest protection scheme: “Quad-Mute.”
❏Efficient heat sinks and a self-contained forced-air cool-
ing system dissipate heat quickly and evenly for extra
amplifier protection and greater power output.
❏Extra rugged, extruded aluminum front panel with ODEP
and signal presence/IOC indicators for each channel,
and an Enable indicator.
❏Mounts in a standard 19-inch (48.3-cm) equipment rack
(units can also be stacked).
❏Three-Year, No-Fault, Full warranty completely protects
your investment and guarantees its specifications.

Macro-Tech
®
602/1202/2402 Po er Amplifiers
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Reference Manual
Fig. 2.1 Front Panel Controls & Indicators
2 Controls, Indicators &
Connectors
A. Dust Filters
The dust filters remove large particles from the air drawn
in by the cooling fan. Check the filters regularly to pre-
vent clogging. The filter elements can be easily re-
moved for cleaning by gently pulling them away from
the front panel (see Sections 3.2 and 4.5).
B. Level Controls
The output level for each channel is set with these con-
venient level controls mounted on the front panel. Each
level control has 31 detents for precise adjustment (see
Section 4.4). A security option is available to prevent
tampering (see Section 8.3).
C. Signal/IOC Indicators
These green multifunction indicators show signal pres-
ence and distortion for each channel. As signal pres-
ence indicators, they flash synchronously with the
output audio signals to show their presence. As IOC
(Input/Output Comparator) indicators, they flash
brightly with a 0.1 second hold delay if there is a differ-
ence of 0.05% or more between the input and output
signal waveforms. This provides proof of distortion-free
performance . Note: The Channel 2 IOC indicator stays
on in Parallel-Mono mode (see Section 4.2).
D. ODEP Indicators
During normal operation of the ODEP (Output Device
Emulation Protection) circuitry, these amber indicators
glow brightly to show the presence of reserve thermal-
dynamic energy. They dim proportionally as energy re-
serves decrease. In the rare event that energy reserves
are depleted, the indicators turn off and ODEP propor-
tionally limits output drive so the amplifier can safely
continue operating even under severe conditions.
These indicators can also help identify more unusual
operating conditions (see Section 4.2).
E. Enable Indicator
This indicator lights when the amplifier has been “en-
abled”or turned on, and AC power is available (see
Section 4.2).
F. Enable Switch
This push button is used to turn the amplifier on and off.
When turned on, the output is muted for approximately
four seconds to protect your system from start-up tran-
sients. (This delay can be changed. Contact Crown’s
Technical Support Group for details.)
G. Power Cord
The power cord has an appropriate plug for the required
voltage. 120 VAC, 60 Hz North American Macro-Tech
602s and 1202s have 14 AWG line cords and NEMA 5-
15P plugs. Macro-Tech 2402s have 12 AWG line cords
and NEMA 5-20P plugs. International units are shipped
with an appropriate line cord and plug. See Section 7
for AC power usage.
H. Stereo/Mono Switch
The three operating modes of a Macro-Tech amplifier
are controlled by this switch. Stereo mode is used for
normal two-channel operation, Bridge-Mono mode is
used to drive a single channel with a load impedance of
at least 4 ohms, and Parallel-Mono mode is used to

Macro-Tech
®
602/1202/2402 Po er Amplifiers
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Reference Manual
Fig. 2.2 Rear Panel Controls & Connectors
(Note: Reset Switches (Item I) only available on the Macro-Tech 2402 model.)
drive a single channel with an impedance less than 4
ohms. Important: Turn off the amplifier before chang-
ing the stereo/mono switch (see Section 3.3).
I. Reset Switches (Macro-Tech 2402 only)
The Macro-Tech 2402 has a back panel Reset switch
for each channel. Each switch resets the circuit breaker
that protects the channel’s power supply from overload.
J. PIP Module
The standard PIP2-FXQ is included with your amplifier.
It provides female three-pin XLR input connectors. A
variety of other PIP modules can be used in place of the
PIP2-FXQ. They add additional features that customize
the amplifier for different applications (see Section 8.1
for information on available PIP modules).
❑Input Sensitivity Switch (not shown)
The three-position input sensitivity switch located inside
the amplifier can be set after removing the PIP module
(J). It is set at the factory to 0.775 volts for standard 1-
kHz output into 8 ohms. It can also be set to 1.4 volts for
standard 1-kHz output into 8 ohms, or a fixed voltage
gain of 26 dB (see Section 4.4).
K. Balanced Phone Jack Inputs
Balanced 1/4-inch phone jack input connectors are pro-
vided on the PIP2-FXQ. The phone jacks can be wired
for either balanced (tip, ring and sleeve) or unbalanced
(tip and sleeve) input signals. Caution: The Channel 2
input should NOT be used in either Bridge Mono or
Parallel Mono mode.
L. Balanced XLR Inputs
The factory-installed PIP2-FXQ provides a three-pin fe-
male XLR connector for balanced input to each chan-
nel. The XLR inputs are connected in parallel with the
amplifier’s phone jack inputs. Because the PIP2-FXQ
does not have any active circuitry, its XLR connectors
can also be used as “daisy chain”outputs to connect
signals from phone jack inputs to multiple amplifiers
(see Section 3.3.4). Caution: The Channel 2 input
should NOT be used in either Bridge Mono or Paral-
lel Mono mode.
M. Output Jacks
A pair of versatile 5-way binding posts is provided for
the output of each channel. The 5-way binding posts
accept banana plugs, spade lugs or bare wire. (Euro-
pean models do not accept banana plugs.)
N. Input Ground Lift Switch
The input ground lift switch is located on the PIP2-FXQ.
It is used to isolate the input signal grounds from the AC
(chassis) ground to help prevent ground loops that can
result in unwanted hum and noise (see Section 3.3.4 for
more information about preventing ground loops).

Macro-Tech
®
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Reference Manual
If the air supply is unusually dusty, you might want to
pre-filter it using commercial furnace filters to prevent
rapid loading of the unit’s own air filter. When needed,
the unit’s filter can be cleaned with mild dish detergent
and water (see Section 4.5).
BLOW R
(OPTION 2)
BLOW R
(OPTION 1)
AIR
FLOW
FRONT
OF
RACK
DOOR
AIR
FLOW
QUIPM NT
RACK
(SID VI W)
Fig. 3.3 Proper Air Flow in a Rack Cabinet
3 Installation
3.1 Mounting
Macro-Tech amplifiers are designed for standard
19-inch (48.3-cm) rack mounting and “stack”mounting
without a cabinet. For more efficient cooling and extra
support in a rack, it is recommended that units be
stacked directly on top of each other.
Important: If the unit will be transported, it should also
be securely supported at the back of the rack.
Fig. 3.2 Top View of a Rack-Mounted Unit
AIR
FLOW
AIR FLOW
AMPLIFI R
(TOP VI W)
RACK
CABIN T
16 in
40.6 cm
2 in
(5 cm)
MIN.
IMPORTANT: Be sure rear of amplifier
is securely mounted to rack.
17 in
43.2 cm
AIR
FLOW
3.2 Cooling
NEVER block the side or front air vents. Macro-Tech
amplifiers do not need to be mounted with space be-
tween them. If you must leave open spaces in a rack for
any reason, close them with blank panels to prevent air
from recycling into the front of other amplifiers. Allow at
least 35 cubic feet (1 cubic meter) per minute per unit
for the Macro-Tech 602 and 1202, and at least 45 cubic
feet (1.3 cubic meters) per minute per unit for the
Macro-Tech 2402. Additional air flow may be required
when driving low impedance loads at consistently high
output levels. Refer to Section 7 for detailed information
on thermal dissipation.
Fig. 3.1 Mounting Dimensions
When mounting the amplifier in a rack, the side walls of
the rack should be at least 2 inches (5 cm) away from
the chassis as shown in Figure 3.2.
Tip: An easy way to verify adequate cooling is to ob-
serve the ODEP indicators while the amplifier is operat-
ing under worst-case conditions. If the indicators dim,
additional cooling is recommended.
If your rack has a front door that could block air flow to
the amplifier’s air intakes, you must provide adequate
air flow by installing a grille in the door or by pressuriz-
ing the air behind the door. Wire grilles are recom-
mended over perforated panels because they tend to
cause less air restriction. A good choice for pressuriz-
ing the air behind a rack cabinet door is to mount a
“squirrel cage”blower inside the rack (Option 1 below).
At the bottom of the rack, mount the blower so it blows
outside air into the space between the door and in front
of the amplifiers, pressurizing the “chimney”behind the
door. This blower should not blow air into or take air out
of the space behind the amplifiers. For racks without a
door, you can evacuate the rack by mounting the blower
at the top of the rack so that air inside the cabinet is
drawn out the back (Option 2 below).

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Reference Manual
3.3 Wiring
This section describes the most common ways to in-
stall your amplifier in a sound system. The input and
output terminals are located on the back panel. Please
use care when making connections, selecting signal
sources and controlling the output level. The load you
save may be your own! Crown assumes no liability for
damaged loads resulting from careless amplifier use or
deliberate overpowering.
CAUTION: Always remove power from the unit and
turn the level controls off while making or changing
connections. This is very important when loudspeak-
ers are connected because it reduces the chance of
loud blasts that can cause loudspeaker damage.
Macro-Tech amplifiers may be operated in one of three
modes (Stereo, Bridge-Mono, and Parallel-Mono) by
switching the stereo/mono switch on the back panel.
There are VERY IMPORTANT wiring differences among
these three modes which will be discussed next.
Fig. 3.4 Stereo Wiring
3.3.1 Stereo (Two-Channel) Operation
In Stereo mode, installation is very intuitive: input Chan-
nel 1 feeds output Channel 1, and input Channel 2 feeds
output Channel 2. To put the amplifier in Stereo mode,
first turn off the amplifier, then slide the stereo/mono
switch to the center position, and properly connect the
output wiring as shown in Figure 3.4. A pair of 5-way
binding posts is provided for each channel to facilitate
easy connection of loudspeaker wires. Observe correct
loudspeaker polarity and be very careful not to short
the two outputs.
CAUTION: In Stereo mode, never parallel the two
outputs by directly tying them together, and never
parallel them with the output of another amplifier.
Such a connection does not result in increased power
output, but may result in overheating and premature
activation of the protection circuitry.
Note: A method for paralleling multiple amplifiers for fail-
safe redundancy is available from Crown’s Technical
Support Group.

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Reference Manual
3.3.2 Bridge-Mono Operation
Bridge-Mono mode is intended for driving loads with a
total impedance of 4 ohms or more (If the load is less
than 4 ohms, see Section 3.3.3). Installing the amplifier
in Bridge-Mono mode is very different from the other
modes and requires special attention.
To put the amplifier in Bridge-Mono mode, turn the am-
plifier off and slide the stereo/mono switch to the right
(as you face the back of the amplifier). Both outputs
receive the signal from Channel 1 with the output of
Channel 2 inverted so it can be bridged with the Chan-
nel 1 output. DO NOT USE THE CHANNEL 2 INPUT or
the signal level and quality may be greatly degraded.
Keep the Channel 2 level control turned down com-
pletely (counterclockwise).
Note: The input jack and level control of Channel 2 are
Fig. 3.5 Bridge-Mono Wiring
not defeated in Bridge-Mono mode. Any signal fed into
Channel 2 will work against and add to or distort the
signal in Channel 1.
Connect the load across the Channel 1 and 2 red bind-
ing posts with the positive lead from the load attaching
to the red post of Channel 1 and the negative lead of the
load attaching to the red post of Channel 2 as shown in
Figure 3.5. THE TWO BLACK BINDING POSTS ARE
NOT USED AND SHOULD NOT BE SHORTED. The
load must be balanced (neither side shorted to ground).
CAUTION: Be certain all equipment (meters,
switches, etc.) connected to the mono output is bal-
anced. To prevent oscillations, both sides of the line
must be isolated from the input grounds.

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Reference Manual
Fig. 3.6 Parallel-Mono Wiring
3.3.3 Parallel-Mono Operation
Parallel-Mono mode is intended for driving loads with a
net impedance of less than 4 ohms. (See Bridge-Mono
if the load is 4 ohms or greater.) Installing the amp in
Parallel-Mono mode is very different from the other
modes and requires special attention.
CAUTION: Do not attempt to operate in Stereo or
Bridge-Mono mode until the Parallel-Mono jumper
is first removed. Failure to do so will result in high
distortion and excessive heating.
To put the amplifier in Parallel-Mono mode, turn it off
and slide the stereo/mono switch to the left (as you face
the back panel). Connect the input signal to Channel 1
only. The Channel 2 input and level control are by-
passed in this mode, so they should not be used.
Note: It is normal for the IOC indicator of Channel 2 to
remain lit in Parallel-Mono mode.
Install a jumper wire between the red binding posts of
both Channel 1 and 2 that is at least 14 gauge in size.
Then, connect the load to the output of Channel 1 as
shown in Figure 3.6. The positive lead from the load
connects to the red binding post of Channel 1 and the
negative lead from the load connects to the black bind-
ing post of Channel 1.
CAUTION: Remove the jumper wire before chang-
ing to Stereo or Bridge-Mono mode.

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Reference Manual
3.3.4 Input Connection
Both the balanced XLR and phone jack inputs have a
nominal impedance of 20 k ohms (10 k ohms with un-
balanced wiring) and will accept the line-level output of
most devices. Female three-pin XLR input connectors
and 1/4-inch jacks are provided on the standard
PIP2-FXQ input module (other PIP modules are de-
scribed in Section 8.1). Correct input wiring will depend
on two factors: (1) whether the input signals are bal-
anced or unbalanced, and (2) whether the signal source
Fig. 3.7 Unbalanced Input Wiring
Fig. 3.9 Balanced and Unbalanced Phone Plugs
Fig. 3.8 Balanced Input Wiring
floats or has a ground reference. Figures 3.7 and 3.8
show the recommended connection techniques for
each type of signal source.
The amplifier’s built-in 1/4-inch phone jack input connec-
tors can be wired similarly for balanced or unbalanced,
floating or ground-referenced sources. They have a
standard tip-ring-sleeve (TRS) configuration: the tip is
positive (+), the ring is negative (–) and the sleeve is
chassis (see Figure 3.9). Wiring for various sources fol-
lows the XLR wiring guidelines shown in Figures 3.7
and 3.8.

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Reference Manual
Please follow the instruction in Section 3.3.2 and 3.3.3 if
the amplifier will be used in either Bridge-Mono or Par-
allel-Mono mode. Remember, do not use the Channel 2
input in either of these mono modes.
SOLVING INPUT PROBLEMS
Sometimes large infrasonic (subaudible) frequencies
are present in the input signal. These can damage loud-
speakers by overloading or overheating them. To at-
Input Wiring Tips
1. Use only shielded cable. Cables with
higher density shields are better. Spiral
wrapped shield is not recommended.
2. When using unbalanced lines, keep the
cables as short as possible. Avoid cable
lengths greater than 10 feet (3 meters).
3. Do not run signal cables together with
high-level wiring such as loudspeaker wires
or AC cords. This greatly lessens the chance
of hum or noise being induced into the input
cables.
4. Turn the entire system off before changing
connections. Turn level controls down
completely before powering the system back
up. Crown is not liable for damage incurred
when any transducer or component is
overdriven.
+
–
Balanced In
910 Ω
.003
F
µ
.015
F
µ
.018
F
µ
1.8 mH
2.5 mH
A
C
B
.015
F
µ
1.8 mH
D
Balanced Out
+
–
910 Ω
1.8 mH
2.5 mH
1.8 mH
+
–
Balanced In Balanced Out
+
–
+
–
Balanced In Balanced Out
+
–
+
–
Balanced In Balanced Out
+
–
0.47 Film
0.47 Film
Fig. 3.12 Balanced RFI Filters
1 Hz 10 Hz 100 Hz 1 kHz 10 kHz
dB
0
–5
–10
–15
1 F
µ
.1 F
µ
.05 F
.01 F
µ
µ
Frequency
Fig. 3.10 Infrasonic Filter Capacitors
tenuate such frequencies, place a capacitor in series
with the input signal line. The graph in Figure 3.10
shows some capacitor values and how they affect the
frequency response. Use only low-leakage paper, mylar
or tantalum capacitors.
Another problem to avoid is the presence of large lev-
els of radio frequencies or RF in the input signal. Al-
though high RF levels may not pose a threat to the
amplifier, they can burn out tweeters or other loads that
are sensitive to high frequencies. Extremely high RF lev-
els can also cause your amplifier to prematurely acti-
vate its protection circuitry, resulting in inefficient
4 kHz 10 kHz 40 kHz 100 kHz
Frequency
dB
0
–10
–20
A
B
C
6 dB/octave
12 dB/octave
To
Amp
GND
To
Amp
GND
To
Amp
GND
Source
1.8 K ohm
.003
Fµ
.015
F
µ
.018
Fµ
3.9 mH
5 mH
600 ohm
Source
R
600 ohm
Source
R
A
C
B
Note: A low source impedance (R) can be
increased to 600 ohms with an appropriate resistor.
Fig. 3.11 Unbalanced RFI Filters
operation. RF can be introduced into the signal by local
radio stations and from the bias signal of many tape
recorders. To prevent high levels of input RF, install an
appropriate low-pass filter in series with the the input
signal. Some examples of unbalanced wiring for low-
pass filters are shown in Figure 3.11.
For balanced input wiring use one of the examples in
Figure 3.12. Filters A, B and C correspond to the unbal-
anced filters above. Filter D also incorporates the infra-
sonic filter described previously.
A third problem to avoid is hum. The two most common
sources of hum in an audio system are inductive cou-
pling and ground loops.
Inductive coupling can occur when input cables are

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Reference Manual
subjected to a magnetic field from a power cord or
power transformer. One way to prevent inductive cou-
pling is to lace the input cables together along their
length and route them as far away as possible from
power transformers and power cords. The use of
shielded pair cable is another effective way to reduce
or eliminate hum resulting from inductive coupling.
Input and output grounds are sometimes tied together
for testing or metering. This can cause feedback oscil-
lation from load current in the test loop. In some sys-
tems, even the AC power line may provide this
feedback path. Proper grounding, input isolation and
isolation of common AC devices in the system is good
practice.
gauge (thickness) for the length being used. The resis-
tance introduced by inadequate loudspeaker cables
will reduce both the output power and the motion con-
Use Good Output Connectors
1. To prevent possible shorts, do not expose
the loudspeaker cable connectors.
2. Do not use connectors that might acci-
dentally tie two channels together when mak-
ing or breaking connections (for example, a
standard three-wire stereo phone plug).
3. Connectors that can be plugged into AC
power receptacles should never be used.
4. Connectors with low current-carrying ca-
pacity should not be used.
5. Connectors with any tendency to short
should never be used.
3.3.5 Output Connection
Consider the power-handling capacity of your load be-
fore connecting it to the amplifier. Crown is not liable for
damage incurred at any time due to overpowering. Fus-
ing loudspeaker lines is highly recommended (see Sec-
tion 3.3.6). Also, please pay close attention to the
precautions provided in Section 4.1.
HOW TO DETERMINE
APPROPRIATE WIRE GAUGE
It is important to use loudspeaker cables with sufficient
40
30
20
15
10
9
8
7
6
5
4
3
2
1
2
5
10
20
50
100
.04
.06
.1
.2
.4
.6
1
2
4
6
10
20
40
5
10
20
50
1
2
100
200
500
1000
2000
5000
8000
5000
1000
500
100
50
10
5
1
.5
.1
.05
.01
#28
#26
#24
#22
#20
#18
#16
#14
#12
#10
#8
#6
#4
#2
#0
#00
#0000
R
LOAD
RESISTANCE
(ohms)
L
R
R
DAMPING
FACTOR
L
S
R
SOURCE
RESISTANCE
(ohms)
S
2-COND.
CABLE
(feet)
COPPER
WIRE
(AWG)
(ohms/1000 ft.)
Example Sho n:
R = 8 ohms; R = 0.016 ohms or D.F. = 500;
Cable Length = 10 ft.; ans er: #8 ire
LS
1
0.5
200
500
1,000
2,000
20,000
5,000
10,000
.01
.001
.02
.004
.006
.002
.0004
.0006
.0002
0.6
0.7
0.8
1.5
0.9
Fig. 3.13 Wire Size Nomograph

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Reference Manual
trol of the loudspeakers. The latter problem occurs be-
cause the damping factor decreases as the cable re-
sistance increases. This is very important because the
amplifier’s excellent damping factor can easily be ne-
gated by insufficient loudspeaker cables.
Use the nomograph in Figure 3.13 and the procedure
that follows to find the recommended wire gauge (AWG
or American Wire Gauge) for your system.
1. Note the load resistance of the loudspeakers connected
to each channel of the amplifier. Mark this value on the
“Load Resistance”line of the nomograph.
2. Select an acceptable damping factor and mark it on the
“Damping Factor”line. Your amplifier can provide an excel-
lent damping factor of 1,000 from 10 to 400 Hz in Stereo
mode with an 8-ohm load. In contrast, typical damping fac-
tors are 50 or lower. Higher damping factors yield lower dis-
tortion and greater motion control over the loudspeakers. A
common damping factor for commercial applications is be-
tween 50 and 100. Higher damping factors may be desir-
able for live sound, but long cable lengths often limit the
highest damping factor that can be achieved practically.
(Under these circumstances, Crown’s IQ System
®is often
used so amplifiers can be monitored and controlled when
they are located very near the loudspeakers.) In recording
studios and home hi-fi, a damping factor of 500 or more is
very desirable.
3. Draw a line through the two points with a pencil, and
continue until it intersects the “Source Resistance”line.
4. On the “2-Cond. Cable”line, mark the length of the
cable run.
5. Draw a pencil line from the mark on the “Source Resis-
tance”line through the mark on the “2-Cond. Cable”line,
and on to intersect the “Annealed Copper Wire”line.
6. The required wire gauge for the selected wire length and
damping factor is the value on the “Annealed Copper Wire”
line. Note: Wire size increases as the AWG gets smaller .
7. If the size of the cable exceeds what you want to use,
(1) find a way to use shorter cables, like using the IQ Sys-
tem, (2) settle for a lower damping factor, or (3) use more
than one cable for each line. Options 1 and 2 will require the
substitution of new values for cable length or damping factor
in the nomograph. For option 3, estimate the effective wire
gauge by subtracting 3 from the apparent wire gauge every
time the number of conductors of equal gauge is doubled.
So, if #10 wire is too large, two #13 wires can be substituted,
or four #16 wires can be used for the same effect.
SOLVING OUTPUT PROBLEMS
Sometimes high-frequency oscillations occur which
can cause your amplifier to prematurely activate its pro-
tection circuitry and result in inefficient operation. The
effects of this problem are similar to the effects of the RF
problem described in Section 3.3.4. To prevent high-
frequency oscillations:
1. Lace together the loudspeaker conductors for
each channel; do not lace together the conduc-
tors from different channels. This minimizes the
chance that cables will act like antennas and
transmit or receive high frequencies that can
cause oscillation.
2. Avoid using shielded loudspeaker cable.
3. Avoid long cable runs where the loudspeaker
cables from different amplifiers share a common
cable tray or cable jacket.
4. Never connect the amplifier’s input and output
grounds together.
5. Never tie the outputs of multiple amplifiers to-
gether.
6. Keep loudspeaker cables well separated from
input cables.
7. Install a low-pass filter on each input line (similar
to the RF filters described in Section 3.3.4).
8. Install input wiring according to the instructions
in Section 3.3.4.
Another problem to avoid is the presence of large sub-
sonic currents when primarily inductive loads are
used. Examples of inductive loads are 70-volt trans-
formers and electrostatic loudspeakers.
Inductive loads can appear as a short circuit at low fre-
quencies. This can cause the amplifier to produce large
low-frequency currents and activate its protection cir-
cuitry. Always take the precaution of installing a high-
pass filter in series with the amplifier’s input when
inductive loads are used. A 3-pole, 18-dB-per-octave
filter with a –3 dB frequency of 50 Hz is recommended
(depending on the application, an even higher –3 dB
frequency may be desirable). Such a filter is described
with infrasonic frequency problems in Section 3.3.4.
Fig. 3.14 Inductive Load (Transformer) Network
4-ohm, 20-watt
Resistor
590 to 708 µF Capacitor
120 VAC, N.P.
+
–
Inductive
Load
+
–
From
Amplifier
Output

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Reference Manual
Another way to prevent the amplifier from prematurely
activating its protection systems and to protect induc-
tive loads from large low-frequency currents is to con-
nect a 590 to 708 µF nonpolarized capacitor and 4-ohm,
20-watt resistor in series with the amplifier’s output and
the positive (+) lead of the transformer. The circuit
shown in Figure 3.14 uses components that are avail-
able from most electronic supply stores.
3.3.6 Additional Load Protection
Macro-Tech amplifiers generate enormous power. If
your loudspeakers do not have built-in protection from
excessive power, it’s a good idea to protect them. Loud-
speakers are subject to thermal damage from sustained
overpowering and mechanical damage from large tran-
sient voltages. Special fuses can be used to protect
your loudspeakers in both cases.
Fig. 3.15 Loudspeaker Fuse Nomograph
Two different types of fuses are required for thermal pro-
tection and voltage protection. Slow-blow fuses are usu-
ally selected to protect loudspeakers from thermal
damage because they are similar to loudspeakers in
the way they respond to thermal conditions over time. In
contrast, high-speed instrument fuses like the Littlefuse
361000 series are used to protect loudspeakers from
large transient voltages. The nomograph in Figure 3.15
can be used to select the properly rated fuse for either
type of loudspeaker protection.
There are basically two approaches that can be taken
when installing fuses for loudspeaker protection. A com-
mon approach is to put a single fuse in series with the
output of each channel. This makes installation conve-
nient because there is only one fuse protecting the loads
on each output. The main disadvantage of this approach
becomes obvious if the fuse blows because none of the
loads will receive any power.
A better approach is to fuse each driver independently.
This allows you to apply the most appropriate protec-
tion for the type of driver being used. In general, low-
frequency drivers (woofers) are most susceptible to
thermal damage and high-frequency drivers (tweeters)
are usually damaged by large transient voltages. This
means that your loudspeakers will tend to have better
protection when the woofers are protected by slow-blow
fuses and high-frequency drivers are protected by high-
speed instrument fuses.
3.4 AC Power Requirements
All Macro-Tech amplifiers are shipped with an appropri-
ate line cord. When possible, use a power receptacle
on a dedicated circuit and always make sure that it can
supply the correct voltage and current. We do not rec-
ommend operating your amplifier on voltages greater
than 10% above or below the unit’s rated voltage. For
example, if your amplifer is rated for 120 VAC, the line
voltage should not exceed 132 VAC. See Section 7 for
power requirements under a variety of conditions.
All specifications in this manual were measured using
120 VAC, 60 Hz power, unless otherwise noted. Specifi-
cations were derived using a voltage that is accurate to
within 0.5% with THD less than 1.0% under all testing
conditions. Performance variations can occur at other
AC voltages and frequencies. In addition, line regula-
tion problems directly affect the output power from the
amplifier.

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Reference Manual
4 Operation
4.1 Precautions
Macro-Tech amplifiers are protected from internal and
external faults, but you should still take the follow pre-
cautions for optimum performance and safety:
1. Improper wiring for Stereo, Bridge-Mono and
Parallel-Mono modes can result in serious oper-
ating difficulties. Refer to Section 3.3 for details.
2. WARNING: Do not change the position of the
stereo/mono switch unless the amplifier is first
turned off.
3. CAUTION: In Parallel-Mono mode, a jumper is
used between the red (+) Channel 1 and 2 output
binding posts. Be sure to remove this jumper for
Stereo or Bridge-Mono mode, otherwise high
distortion and excessive heating will definitely
occur. Check the stereo/mono switch on the back
panel for proper position.
4. Turn off the amplifier and unplug it from the AC
mains before removing the PIP module.
5. Use care when making connections, selecting sig-
nal sources and controlling the output level. The
load you save may be your own.
6. Do not short the ground lead of an output cable to
the input signal ground. This may form a ground
loop and cause oscillations.
7. Operate the amplifier from AC mains of not more
than 10% variation above or below the selected line
voltage and only the specified line frequency.
8. Never connect the output to a power supply out-
put, battery or power main. Such connections may
result in electrical shock.
9. Tampering with the circuitry by unqualified person-
nel, or making unauthorized circuit changes invali-
dates the warranty.
Remember: Crown is not liable for damage that results
from overdriving other system components.
4.2 Indicators
The amber nable indicator is provided to show that
the amplifier has been turned on (or enabled), and that
its low-voltage power supply and forced-air cooling sys-
tem are working. It does not indicate the status of the
high-voltage power supplies. For example, the Enable
indicator will remain lit during unusual conditions that
would cause the amplifier’s protection systems to put a
Fig. 4.1 Indicators
high-voltage power supply in “standby”mode (see Sec-
tion 4.3.2).
The amber OD P indicators confirm the normal op-
eration of Crown’s patented Output Device Emulation
Protection circuitry. During normal operation, they glow
brightly to show the presence of reserve thermal-dy-
namic energy. They dim proportionally as the energy
reserve decreases. In the rare event that there is no re-
serve, the indicators turn off and ODEP proportionally
limits the drive level of the output stages so the ampli-
fier can continue safe operation even when conditions
are severe. (For a more detailed description of ODEP,
see Section 4.3.1.)
The ODEP indicator for the affected channel will turn off
if a high-voltage power supply is put in “standby”mode,
a high-voltage power supply fuse (or breaker) blows, or
a transformer activates its thermal protection circuitry
(see Section 4.3.2). Both ODEP indicators turn off if the
amplifier loses AC power, the power switch is turned off
or the low-voltage power supply fuse blows.
The green Signal/IOC indicators show signal presence
and distortion. As signal presence indicators, they flash
with normal intensity in sync with the output audio sig-
nals. As IOC (Input/Output Comparator) indicators, they
flash brightly if there is any difference between the input
and output signal waveforms greater than 0.05%. Be-
cause transient distortion happens quickly, a 0.1 sec-
ond “hold delay”keeps the indicators on long enough
to be easily noticed. The IOC function essentially pro-
vides proof of distortion-free performance . Note: The
Channel 2 IOC indicator will remain lit when running in
Parallel-Mono mode.
Under conditions where one of the amplifier’s high-volt-
age power supplies is temporarily put in standby mode,
the Signal/IOC indicators will stay on with full bright-
ness. They will resume normal operation when the am-
plifier is no longer in standby mode.
Note: See Figure 4.2 for an explanation of the conditions
that may activate standby mode.